Testosterone Propionate dramatically increases nitrogen retention in the muscle allowing protein to be stored in the muscle to a larger degree; as protein is the building block of muscle and increased lean tissue improves our metabolic rate, on this basis alone we have a highly desirable hormone; however, the good news does not end there. As by its mode of action testosterone has the ability to block and reduce muscle wasting hormones known as glucocortico steroid, most commonly cortisol. While testosterone truly has seemingly limitless properties, as it pertains to performance, of particular interest is its ability to greatly increase IGF 1 production in the body; as you understand IGF 1 is a very powerful peptide hormone of a highly anabolic nature and plays a key role alongside human growth hormone, another potent peptide based hormone.